Previously published
This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here.
The simple servo sequencer that I’ve been working on has exposed a bug in the servo controller firmware. The bug is due to stack corruption during movement completion notifications, so it only happens if you use the ‘multi-move’ commands or the delay move command.
Previously published
This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here.
Once the servo controller code was feature complete I switched to looking at the hardware side of things and thinking about the next stage, the servo sequencing.
From a hardware point of view I had several things to work on.
I’ve complained about DevPartner Studio enough in the past (here, here, here, etc.) that I thought I should write a positive blog posting since my recent experiences have been very positive.
Some time ago I reported a bug in the BoundsChecker part of the product which meant that it hung sometimes in multi-threaded code. I managed to get a reasonably straight forward reproduction and raised an issue with them. It took a while but this is now fixed in 9.
Charles Dickens said it best in A Tale of Two Cities; “It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair, we had everything before us, we had nothing before us, we were all going direct to heaven, we were all going direct the other way”.
The filtering API that’s built into the stream (i.e. TCP) side of the licensed framework is pretty powerful. It’s what the OpenSSL, SChannel and SSPI Negotiate filters use to transform the data as it flows into and out of your server without you needing to do anything special; it’s what the flow control filter uses to provide efficient TCP window based flow control; it’s what the compression filter uses to compress your data stream; it’s what the read timeout filter uses to provide you with asynchronous read timeouts on overlapped I/O and what the connection re-establishment filter uses to automatically reconnect if your connection goes down.
Previously published
This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here.
Whilst playing around with my servo controller I realised that the power used by a servo goes up considerably when it’s under heavy load (such as when it’s pressing against the table and still trying to move). I can, potentially, get an idea of this load by measuring the current that each servo is using and using this feedback somehow.
Previously published
This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here.
I decided to treat myself to an early christmas present and bought a 60W temperature controlled soldering station (a ZD-916 which I got from Maplin). All I can say is WOW. Suddenly I can solder neatly rather than making a smeary mess.
Previously published
This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here.
This is the AVR Studio project and assembly language source code files for the latest version (v7.0) of my 64 channel serial servo controller.
This is the latest version of the ATMega168 version of the code which includes all of the new servo commands that I wrote about here including the multi-move command and the unit tests that I spoke of here.
Previously published
This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here.
The latest version of the serial servo controller is now fully operational (I’ll upload the source code shortly). There are still some bugs that I’m finding but the work I put in to getting the unit tests in place makes fixing these bugs pretty straight forward.
I’ve been spending a little time recently writing a custom Wireshark dissector plugin for the UDT protocol. This didn’t prove to be that difficult once I got over the initial problem of actually getting the Wireshark source to build with VS2008. My problem was that I’d found a CodeProject article which is now slightly out of date and which I followed too closely - setting up the Platform SDK version that the article stated was required.
